Have you pulled a dummy round and measured the very edge of the base band. Surprising how often a boolit can swage down in the case especially one that is seated deeper. When the base starts in on the thicker part of the web of the brass a nice .452” boolit can easily become much smaller in diameter. Also allowing a boolit to age before loading is important as well. Case swage can be an issue and when I load the 454640 HP, originally a 260 grain solid, and it seats quite deep in the 45 ACP case so I have to make sure I use an expander die to open up the brass or I end up with a boolit that has a base of .449” and to no surprise the soft HP leads like crazy.